1. Field of the Invention
This invention relates to telephony products and, more specifically, to a telephone line connection and disconnection circuit which does not require the use of a relay. By eliminating the need for a relay, the telephone line connection and disconnection circuit will consume less power and be less expensive to produce.
2. Description of the Prior Art
Many telephone adjunct boxes are required to disconnect the associate telephone from the telephone line. The reason for requiring the disconnection of the telephone from the telephone line is to suppress the telephone ringing and to mute the telephone conversation during a call. It is also the best way to check if another extension is in the off-hook condition. Presently, all devices which connect or disconnect the associate telephone from the telephone adjunct box use some type of relay for switching.
While relays do work, there are several problems associated with there use. First, mechanical relays are very large and bulky. Thus, the circuits that are used to connect and disconnect the associate telephone from the telephone adjunct box tend to be large and bulky. Furthermore, mechanical relays consume more power than other types of switches. While there are other types of relays which are smaller in size, such as solid state relays, solid state relays are more expensive to build and implement thus driving up the cost of the circuit used to connect and/or disconnect the associate telephone from the telephone adjunct box. Another problem with using relays is the noise that these types of devices create. Generally, when switching a relay from one position to another, there is noise that is generated. The noise will generally be a clicking sound when the relay changes position. While the noise generally will not interfere with the operation of the circuitry, it""s very annoying to the end user.
Therefore, a need existed to provide an improved circuit for connecting and disconnecting an associate telephone from a telephone adjunct box. The improved circuit must reduce the size of present circuits which use mechanical relays. The improved circuit must also reduce the amount of power consumed by present circuits which use mechanical relays. The improved circuit must further eliminate the noise involved when connecting and disconnecting the associate telephone from a telephone adjunct box. Finally, the improved circuit must be fairly inexpensive to build and operate.
In accordance with one embodiment of the present invention, it is an object of the present invention to provide an improved circuit for connecting and/or disconnecting an associate telephone from a telephone adjunct box.
It is another object of the present invention to provide an improved circuit for connecting and/or disconnecting an associate telephone from a telephone adjunct box that reduces the size of present circuits which use mechanical relays.
It is still another object of the present invention to provide an improved circuit for connecting and/or disconnecting an associate telephone from a telephone adjunct box that reduces the amount of power consumed by present circuits which use mechanical relays.
It is yet another object of the present invention to provide an improved circuit for connecting and/or disconnecting an associate telephone from a telephone adjunct box that eliminates the noise involved when connecting and/or disconnecting the associate telephone from a telephone adjunct box.
It is still a further object of the present invention to provide an improved circuit for connecting and/or disconnecting an associate telephone from a telephone adjunct box that is inexpensive to build and operate.
In accordance with one embodiment of the present invention a telephone line connection and disconnection circuit is disclosed. The circuit has a diode bridge coupled to the telephone line which converts different voltages of the telephone line into a voltage referenced to ground. A switching circuit is coupled to the diode bridge which opens and closes a conductive pathway for connecting and disconnecting a telephony product from the telephone line. A resistive element is coupled to the diode bridge and the switching circuit which allows for the conductive pathway to be normally closed. An optical isolator is coupled to the switching circuit and the resistive element for sending a control signal to the circuit when required.
The foregoing and other objects, features, and advantages of the invention will be apparent from the following, more particular, description of the preferred embodiments of the invention, as illustrated in the accompanying drawing.